net: phy: bcm7xxx: Fix shadow mode 2 disabling

The clear and set masks in the call to phy_set_clr_bits() called from
bcm7xxx_config_init() are inverted. We need to fix this by swapping the two
arguments, that is, set 0 bits, but clear the shade mode 2 enable bit.

Fixes: b560a58c ("net: phy: add Broadcom BCM7xxx internal PHY driver")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>